1/* 2 * RoQ audio encoder 3 * 4 * Copyright (c) 2005 Eric Lasota 5 * Based on RoQ specs (c)2001 Tim Ferguson 6 * 7 * This file is part of FFmpeg. 8 * 9 * FFmpeg is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU Lesser General Public 11 * License as published by the Free Software Foundation; either 12 * version 2.1 of the License, or (at your option) any later version. 13 * 14 * FFmpeg is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with FFmpeg; if not, write to the Free Software 21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 22 */ 23 24#include "avcodec.h" 25#include "bytestream.h" 26#include "internal.h" 27#include "mathops.h" 28 29#define ROQ_FRAME_SIZE 735 30#define ROQ_HEADER_SIZE 8 31 32#define MAX_DPCM (127*127) 33 34 35typedef struct 36{ 37 short lastSample[2]; 38 int input_frames; 39 int buffered_samples; 40 int16_t *frame_buffer; 41 int64_t first_pts; 42} ROQDPCMContext; 43 44 45static av_cold int roq_dpcm_encode_close(AVCodecContext *avctx) 46{ 47 ROQDPCMContext *context = avctx->priv_data; 48 49 av_freep(&context->frame_buffer); 50 51 return 0; 52} 53 54static av_cold int roq_dpcm_encode_init(AVCodecContext *avctx) 55{ 56 ROQDPCMContext *context = avctx->priv_data; 57 int ret; 58 59 if (avctx->channels > 2) { 60 av_log(avctx, AV_LOG_ERROR, "Audio must be mono or stereo\n"); 61 return AVERROR(EINVAL); 62 } 63 if (avctx->sample_rate != 22050) { 64 av_log(avctx, AV_LOG_ERROR, "Audio must be 22050 Hz\n"); 65 return AVERROR(EINVAL); 66 } 67 68 avctx->frame_size = ROQ_FRAME_SIZE; 69 avctx->bit_rate = (ROQ_HEADER_SIZE + ROQ_FRAME_SIZE * avctx->channels) * 70 (22050 / ROQ_FRAME_SIZE) * 8; 71 72 context->frame_buffer = av_malloc(8 * ROQ_FRAME_SIZE * avctx->channels * 73 sizeof(*context->frame_buffer)); 74 if (!context->frame_buffer) { 75 ret = AVERROR(ENOMEM); 76 goto error; 77 } 78 79 context->lastSample[0] = context->lastSample[1] = 0; 80 81 return 0; 82error: 83 roq_dpcm_encode_close(avctx); 84 return ret; 85} 86 87static unsigned char dpcm_predict(short *previous, short current) 88{ 89 int diff; 90 int negative; 91 int result; 92 int predicted; 93 94 diff = current - *previous; 95 96 negative = diff<0; 97 diff = FFABS(diff); 98 99 if (diff >= MAX_DPCM) 100 result = 127; 101 else { 102 result = ff_sqrt(diff); 103 result += diff > result*result+result; 104 } 105 106 /* See if this overflows */ 107 retry: 108 diff = result*result; 109 if (negative) 110 diff = -diff; 111 predicted = *previous + diff; 112 113 /* If it overflows, back off a step */ 114 if (predicted > 32767 || predicted < -32768) { 115 result--; 116 goto retry; 117 } 118 119 /* Add the sign bit */ 120 result |= negative << 7; //if (negative) result |= 128; 121 122 *previous = predicted; 123 124 return result; 125} 126 127static int roq_dpcm_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, 128 const AVFrame *frame, int *got_packet_ptr) 129{ 130 int i, stereo, data_size, ret; 131 const int16_t *in = frame ? (const int16_t *)frame->data[0] : NULL; 132 uint8_t *out; 133 ROQDPCMContext *context = avctx->priv_data; 134 135 stereo = (avctx->channels == 2); 136 137 if (!in && context->input_frames >= 8) 138 return 0; 139 140 if (in && context->input_frames < 8) { 141 memcpy(&context->frame_buffer[context->buffered_samples * avctx->channels], 142 in, avctx->frame_size * avctx->channels * sizeof(*in)); 143 context->buffered_samples += avctx->frame_size; 144 if (context->input_frames == 0) 145 context->first_pts = frame->pts; 146 if (context->input_frames < 7) { 147 context->input_frames++; 148 return 0; 149 } 150 } 151 if (context->input_frames < 8) { 152 in = context->frame_buffer; 153 } 154 155 if (stereo) { 156 context->lastSample[0] &= 0xFF00; 157 context->lastSample[1] &= 0xFF00; 158 } 159 160 if (context->input_frames == 7) 161 data_size = avctx->channels * context->buffered_samples; 162 else 163 data_size = avctx->channels * avctx->frame_size; 164 165 if ((ret = ff_alloc_packet2(avctx, avpkt, ROQ_HEADER_SIZE + data_size)) < 0) 166 return ret; 167 out = avpkt->data; 168 169 bytestream_put_byte(&out, stereo ? 0x21 : 0x20); 170 bytestream_put_byte(&out, 0x10); 171 bytestream_put_le32(&out, data_size); 172 173 if (stereo) { 174 bytestream_put_byte(&out, (context->lastSample[1])>>8); 175 bytestream_put_byte(&out, (context->lastSample[0])>>8); 176 } else 177 bytestream_put_le16(&out, context->lastSample[0]); 178 179 /* Write the actual samples */ 180 for (i = 0; i < data_size; i++) 181 *out++ = dpcm_predict(&context->lastSample[i & 1], *in++); 182 183 avpkt->pts = context->input_frames <= 7 ? context->first_pts : frame->pts; 184 avpkt->duration = data_size / avctx->channels; 185 186 context->input_frames++; 187 if (!in) 188 context->input_frames = FFMAX(context->input_frames, 8); 189 190 *got_packet_ptr = 1; 191 return 0; 192} 193 194AVCodec ff_roq_dpcm_encoder = { 195 .name = "roq_dpcm", 196 .long_name = NULL_IF_CONFIG_SMALL("id RoQ DPCM"), 197 .type = AVMEDIA_TYPE_AUDIO, 198 .id = AV_CODEC_ID_ROQ_DPCM, 199 .priv_data_size = sizeof(ROQDPCMContext), 200 .init = roq_dpcm_encode_init, 201 .encode2 = roq_dpcm_encode_frame, 202 .close = roq_dpcm_encode_close, 203 .capabilities = CODEC_CAP_DELAY, 204 .sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16, 205 AV_SAMPLE_FMT_NONE }, 206}; 207